1. Field of the Invention
This invention relates to a position detecting apparatus adapted for detecting a change, etc. of position resulting from movement based on manual operation to deliver information thereof to a computer system, etc.
2. Description of the Related Art
Hitherto, it was not possible to move the cursor (or pointer) on a display screen of a computer system unless an operator (or user) operates key board. In recent years, however, cursor control has been connected to a serial port of the computer system, thereby making it possible to move the cursor more freely than the key board.
As an example of one of such cursor controllers, there is known a so called mouse having an outside dimension as large as the palm of the hand and having a ball rotatably provided therewithin. In operation, the human being holds the mouse by the hand to move it on a desk, whereby the ball rotates. Rotation of the ball is detected by an optical encoder. This optical encoder detects rotation of the ball to thereby form position information for moving the cursor and distance information indicating the distance to deliver the information to the computer system through the serial port. The computer system gives an indication to move the cursor on the display screen on the basis of the position information and the distance information delivered from the optical encoder to display picture data corresponding thereto.
As another cursor controller, a so called tablet is known. In the case of the tablet, an operator moves a stay write pen on a dedicated board comprised of an optical grid to thereby count signals indicating the number of crossing times of the optical grid to detect the direction and the position to deliver respective detection information thus obtained to the computer system. The computer system gives an indication to move the cursor on the display screen on the basis of the respective detection information.
Further, in the Japanese Patent Application Laid Open No. 120424/1985 (Tokkaisho No. 60-120424), there is disclosed a position detecting apparatus in which a plurality of marks disposed equidistantly from each other are painted on the spherical surface of a sphere provided at one end of a tubular case and light is irradiated onto these marks and rays of reflected light are detected by using an optical detector, thus position information and distance information are outputted
However, since the mouse has dimensions as large as the palm of the hand of a human being, and an operator is therefore required to hold the mouse in a manner to cover it from above when in use, movement of the hand in a manner different from that when the operator usually holds the mouse is required for inputting characters or graphics to the computer system, resulting in the problem that the operability is poor.
Further, the tablet requires a dedicated board that is paired with the stay write pen, resulting in the problem that movement of the stay write pen is limited also by the dimensions of the board.
In addition, the position detecting apparatus disclosed in the Japanese Patent Application Laid Open No. 120424/1985 (Tokkaisho No. 60-120424) is compact as compared to the mouse, and does not require a dedicated board which was required for the tablet. However, since predetermined marks are painted on the spherical surface of the sphere, there is the problem in durability that those marks are peeled away when such position detecting apparatus is used for long time. Further, in order to allow the human being to use the position detector in the same manner as in the case where the human being ordinarily uses the pen, it is necessary to reduce the shape itself approximately to that of a so called ball-point pen. Followed by this, it is necessary to reduce the dimension of the sphere to approximately several mm. For this reason, it becomes difficult to precisely paint marks on the sphere itself, thus disadvantageously failing to precisely carry out position detection.